A driving circuit of a brushless motor used in an electric power steering system includes switching elements such as FETs (Field Effect Transistors). When the switching element fails, the brushless motor becomes a load when operating the steering wheel, and steering may become heavy. In order to cope with this problem, a relay is inserted in the connection between the brushless motor and the driving circuit. For example, in a case of a three-phase brushless motor, relays are inserted in motor connections of two phases, respectively, and when control is not performed and when the switching element fails, the relays are turned off.